Oil and Gas Reserve Data - Summary of Proved Developed and Undeveloped Reserves (Details)	Mar. 31, 2013 bbl	Mar. 31, 2012 bbl	Mar. 31, 2011 bbl	Mar. 31, 2010 bbl
Proved Undeveloped Reserves	3,806,941	3,995,462
Oil [Member]
Proved Developed Reserves	237,420	194,620	159,975	141,980
Proved Undeveloped Reserves	128,290	151,733	130,187	98,088
Natural Gas [Member]
Proved Developed Reserves	4,807,020	5,359,670	4,964,061	5,017,342
Proved Undeveloped Reserves	3,037,180	3,085,064	3,792,974	3,388,248